Processes for producing expandable pelletized material which comprises polylactic acid (moldable foams which comprise polylactic acid) have been described in general terms in WO 01/012706, but there is no mention of the specific polylactic acid mixture (see components i) to iv) in step a) or of the advantageous mode of operation via pressurized underwater pelletization (see steps c) to e) of the invention). There are wide ranges where this process does not give reproducible moldable foams and in particular does not prevent the premature foaming of the expandable pelletized material.
WO 08/130226 describes a complicated multistage process for producing expandable pelletized material which comprises polylactic acid, where the polylactic acid beads are coated and then post-impregnated with carbon dioxide, or the beads are post-impregnated with carbon dioxide and then coated. The post-impregnation with carbon dioxide leads to prefoamed beads, and this completely changes the technology for further processing of the moldable foams.